sitka spruce: uses, growth, management. 23 



which spreads quickly through the sound wood and renders much 

 of the upper trunk unmerchantable. Damage from this cause is 

 very common in trees over 300 years of age., Wind-shake is a me- 

 chanical defect resulting from heavy stresses in the butt section 

 which are caused by the action of severe winds, and is of infrequent 

 occurrence in large trees. This circular or radial rupture of the 

 wood considerably reduces the value of the tree for lumber. 



BURLS. 



Another injury is the formation of huge burls along the trunks. 

 This defect has been found abundantly in a limited area in Oregon. 

 The illustrations in Plate XIX are typical examples of the defect. 

 Its cause is uncertain, though probably a'nalogous to similar mal- 

 formations in many other species. 



FIRE. 



Sitka spruce is fortunate in having as its habitat a region in 

 which there is less forest-fire hazard than in most parts of the conif- 

 erous forest regions of western North America. Frequent rains 

 throughout the year in southeastern Alaska make fires in the virgin 

 spruce woods there quite uncommon; farther south in Washington 

 and Oregon there is more danger of forest fires in the short dry 

 season. Fires in this region are apt to run in the crowns of the 

 trees, and they do so even in the spring months when the surface 

 litter is still too wet to burn. The moss that hangs on the branches 

 of the hemlock, spruce, and fir trees is very inflammable and helps 

 to carry fire. The spruce region of Oregon suffered from several 

 very disastrous and widespread fires a few decades ago, as the 

 " burns " of the Coast Range witness. 



Sitka spruce is very susceptible to fire. This is due chiefly to its 

 thin bark, which at stump height is only a half-inch to an inch 

 thick. Fire-scars are uncommon in Sitka spruce, for even a very 

 light surface fire is sufficient to kill the cambium, and the trees, 

 thus girdled, die. 



Although an individual tree of Sitka spruce is more susceptible 

 to injury than a Douglas fir of the same size, the forest in which it 

 grows along the coast is less subject to fire than the forest farther 

 inland where Douglas fir predominates. Even though the danger of 

 uncontrollable fires is less in the Coast Range than in the Cascade' 

 Range, careful fire protection in both regions is imperative. 



GROWTH. 



a spruce is one of (be most rapid-growing coniferous species 

 in the Pacific Northwest. In keeping with the character of spruces 

 in general, if- growth during the first few years is less khan thai <>t" 



